Evaluation of chemical and microscopical methods for mass detection of bacteriuria

Uriglox and quantitative urine microscopy in diagnosis of urinary tract infection

The aim of this study was to find an alternative to the sole use of abundant cultural findings as a basis for the diagnosis of urinary tract infection (UTI). For this purpose, the results obtained from the bacteriological culture of daytime urine specimens from 154 students by the dip slide method were checked against the findings from the quantitative culture, microscopy and Uriglox testing of the first morning urines voided later at home. As a diagnostic criterion, the finding of 10(5) or more bacteria/ml urine in two successive cultures had an error of 19%. For the simultaneous occurrence in the morning urine of abundant bacteria (larger than or equal to 10(5)/ml) and a subnormal glucose concentration (as revealed by the Uriglox test), this error was 1.5%. Only the latter combination showed, therefore, the presence of UTI at the confidence level of larger than or equal to 95%, or was "clinically significant". The specificity indices for the Uriglox test and the quantitative culture were 0.99 and 0.97, respectively. Microscopy of the morning urine showed 10(3) or more bacteria/ml in all the subjects with infection but the number of leucocytes was normal in a fifth of them. The specificity indices for microscopic counts of 10(3) or more organisms/ml and 10 or more leucocytes/mm3 were 0.74 and 0.94, respectively. For higher counts, i.e. 10(5) or more bacteria/ml and 50 or more leucocytes/mm3, the specificity index of positive microscopy was 1.0. This specificity level was, however, attained at the expense of the sensitivity, which for 10(5) or more organisms/ml was 0.67 and for 50 or more leucocytes/mm3 0.53. It is concluded that abundant bacterial contamination of specimens often decisively complicates the diagnostic use of urine culture, and therefore the combined use of quantitative culture, microscopy and the Uriglox test is recommended as the principal tool for the diagnosis of UTI in ordinary hospital and ambulatory health services.

Mass detection of bacteriuria by combination of two screening tests

The Uriglox screening test was compared with the modified Griess Nitrite test and with standard urine cultures in the detection of significant bacteriuria on 400 ambulant and asymptomatic residents of the Athens Home for the Aged. The modified Nitrite test alone detected 62%, and the Uriglox test 79% of the 103 cases with positive urine cultures in the examined group. There was significant overlap in the positive cases picked up by each screening test separately, the Uriglox test identifying more Klebsiella infections. Since there were no false-positive cases with either one of the employed tests, the cases identified by one or the other or both screening tests amounted to 95% of the total number of bacteriuric samples. The combination of the moderately sensitive but highly specific test of Nitrite, with the very sensitive test of Uriglox, can effectively substitute for the expensive and time-consuming quantitative bacterial counts with pour-plate techniques in mass screening for bacteriuria.